A system comprises a faceted structure imaging assembly and a faceted structure image analyzer. The system is configured to determine carat weight of a gemstone while in a mounted setting. In a first mode, the imaging assembly obtains a first image of a top gemstone surface. The image analyzer uses the first image to obtain at least one gemstone dimension, such as table and diameter dimensions. In a second mode, the imaging assembly obtains a second image of the top gemstone surface while a colored light pattern is reflected onto the gemstone. The image analyzer uses the second image to obtain at least one other gemstone dimension, such as crown and pavilion angles. The image analyzer uses the dimensions obtained from the first and second images to determine weight information of the gemstone. The system quickly determines gemstone weight reliably and consistently without skilled gemologists or removal from the setting.

An implementation cost of a line-scan optical coherence tomography (OCT) apparatus is reduced by miniaturizing a scanning mirror and using a light source with relaxed requirement in intensity uniformity. The mirror reflects a probe light beam to different parts of a sample for line-scanning the sample. A line-compressing lens compresses the probe light beam's cross-sectional length before the beam reaches the mirror, allowing the mirror to be miniaturized to reflect only the compressed beam. In generating a linear light beam that gives the probe light beam, a cascade of collimating lens, Powell lens and focusing lens generates the linear light beam from a raw light beam of a point source. A slit further filters the linear light beam to remove a peripheral portion thereof such that the linear light beam is substantially uniform in intensity even if an asymmetrical divergent light source is used.

The source light having a range of optical wavelengths is split into sample light and reference light. The sample light is delivered into a sample, such that the sample light is scattered by the sample, resulting in signal light that exits the sample. The signal light and the reference light are combined into an interference light pattern having optical modes having oscillation frequency components respectively corresponding to optical pathlengths extending through the sample. Different sets of the optical modes of the interference light pattern are respectively detected, and high-bandwidth analog signals representative of the optical modes of the interference light pattern are output. The high-bandwidth analog signals are parallel processed, and mid-bandwidth digital signals are output. The mid-bandwidth digital signals are processed over an i number of iterations, and a plurality of low-bandwidth digital signals are output on the ith iteration. The sample is analyzed based on the low-bandwidth digital signals.

An apparatus and method are provided. The apparatus includes an imaging device; a stage movable relative to the imaging device; an isolation plate provided between the imaging device and the stage, including a horizontal glass plate; and a plurality of interferometers in electronic communication with a processor. The plurality of interferometers include three interferometers disposed on the imaging device, configured to direct a first beam set in a first direction toward the horizontal glass plate; and three interferometers disposed on the stage, configured to direct a second beam set in a second direction toward the horizontal glass plate, the second direction being opposite to the first direction. The processor is configured to measure distances between the imaging device and the isolation plate and distances between the stage and the isolation plate based on the first beam set and the second beam set reflected from the horizontal glass plate.

An overlay metrology system may include an illumination source and illumination optics to illuminate an overlay target on a sample with illumination from the illumination source as the sample is in motion with respect to the illumination from the illumination source in accordance with a measurement recipe. The overlay target may include one or more cells, where a single cell is suitable for measurement along a particular direction. Such a cell may include two or more gratings with different pitches. Further, the system may include two or more photodetectors, each configured to capture three diffraction lobes from the two or more grating structures. The system may further include a controller to determine an overlay measurement associated with each cell of the overlay target.

A focus scan type imaging device for imaging a target object in a sample that induces aberration proposed. The device includes: a light source unit for emitting a beam; an optical interferometer for splitting the beam emitted from the light source into a sample wave and a reference wave, and providing an interference wave formed by interference between a reflection wave that is the sample wave reflected from the sample and the reference wave; a camera module for imaging the interference wave; a scanning mirror disposed on an optical path of the sample wave of the optical interferometer and configured to reflect the sample wave to cause the sample wave to scan the sample; a wavefront shaping modulator disposed on the optical path of the sample wave of the optical interferometer; and an imaging controller configured to operate in a phase map calculation mode and in an imaging mode.

A method of improving axial resolution of interferometric measurements of a 3D feature of a sample may comprise illuminating the feature using a first limited number of successively different wavelengths of light at a time; generating an image of at least the 3D feature based on intensities of light reflected from the feature at each of the successively different wavelengths of light; measuring a fringe pattern of intensity values for each corresponding pixel of the generated images; resampling the measured fringe patterns as k-space interferograms; estimating interference fringe patterns for a spectral range that is longer than available from the generated images using the k-space interferograms; appending the estimated interference fringe patterns to the respective measured fringe patterns; and measuring the height or depth of the 3D feature using the measured interference fringe patterns and appended estimated fringe patterns.

An implementation cost of a line-scan optical coherence tomography (OCT) apparatus is reduced by miniaturizing a scanning mirror and using a light source with relaxed requirement in intensity uniformity. The mirror reflects a probe light beam to different parts of a sample for line-scanning the sample. A line-compressing lens compresses the probe light beam's cross-sectional length before the beam reaches the mirror, allowing the mirror to be miniaturized to reflect only the compressed beam. In generating a linear light beam that gives the probe light beam, a cascade of collimating lens, Powell lens and focusing lens generates the linear light beam from a raw light beam of a point source. A slit further filters the linear light beam to remove a peripheral portion thereof such that the linear light beam is substantially uniform in intensity even if an asymmetrical divergent light source is used.

A crack measuring apparatus includes distance-measuring units, an image pickup unit having pixels the positions of which are identified on an imaging device, an infrared image pickup unit having pixels the positions of which are identified on an imaging device and having sensitivity to infrared rays, driving units, angle-measuring units, and an arithmetic control unit, the arithmetic control unit searches for a cracked portion from a temperature difference in an infrared image by turning the infrared image pickup unit, captures an image of the cracked portion by the image pickup unit and identifies a position of the cracked portion from a density difference in the captured image, measures the position of the cracked portion by the distance-measuring units and the angle-measuring units, and acquires three-dimensional absolute coordinates of the cracked portion.

A method for measuring a bond gap includes receiving a light beam at a first interferometer cavity and a reference interferometer cavity, in which the first interferometer cavity is defined by a first surface and a contact interface, and the contact interface is defined by a contact gap less than 1 μm. The method includes determining a first interference amplitude of the first interferometer cavity and a second interference amplitude of the reference interferometer cavity by applying wavelength tuning and spectral analysis to measured intensities of light from the first interferometer cavity and the reference interferometer cavity. The contact gap is determined based on a ratio of the first interference amplitude and the second interference amplitude and information about a mapping between various interference amplitude ratios and expected contact gap values.